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Bismuth–Ceramic Nanocomposites with Unusual Thermal Stability via High‐Energy Ball Milling
Author(s) -
Meitl M.A.,
Dellinger T.M.,
Braun P.V.
Publication year - 2003
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200304433
Subject(s) - materials science , bismuth , ball mill , ceramic , nanocomposite , differential scanning calorimetry , crystallite , nanoparticle , melting point , chemical engineering , thermal stability , cubic zirconia , composite material , transmission electron microscopy , nanotechnology , metallurgy , thermodynamics , physics , engineering
Electrically conducting nanocomposites of bismuth metal and insulating ceramic phases of SiO 2 and MgO were generated via high‐energy ball milling for 24 h using zirconia milling media. The resulting nanocomposites contain Bi nanoparticles with sizes down to 5 nm in diameter. The morphology is a strong function of the oxide phase: specifically, the Bi appears to wet MgO while it forms spherical nanoparticles on the SiO 2 . X‐ray diffraction measurements indicate a nominal bismuth grain size of 50 nm, and peak fitting to a simple bidisperse model yields a mixture of approximately 57 % bulk bismuth and 43 % 27 nm diameter crystallites. Nanoparticles as small as 5 nm are observed in transmission electron microscopy (TEM), but may not constitute a significant volume fraction of the sample. Differential scanning calorimetry reveals dramatic broadening in the temperatures over which melting and freezing occur and a surprising persistence of nanostructure after thermal cycling above the melting point of the Bi phase.